The home page is the first page seen when someone comes to your website. You can edit this page in Site Content -> Manage Home Page.
There are certain features available just for this page under the text editor area.
Once you have created sections, you can select from those sections to show on the home. Click here to view an article on setting up featured sections.
This allows you to display most recent content added to your website either by sections / categories or from all sections. Basically creating a list of avaialable galleries.
Add a Find My Photos Form
You can add a find my photos form on the home page where a customer can enter in their gallery password and be taken directly to their photos without having to navigate to the gallery.
When editing your home page, click the "more options" link, scroll down and check the option to add the form.